1. Field of the Invention
The present invention relates to a torque converter provided in a vehicle and particularly to a support structure for the stator of the torque converter.
2. Description of the Related Art
A torque converter, commonly provided in the power transmission path between the drive source and the automatic transmission of a vehicle, is a fluid drive device that multiplies the torque generated by the drive source and transmits the torque to the automatic transmission. A torque converter generally has a pump impeller that is rotatably driven by the drive source, such as an engine, a turbine runner that is rotated by operating fluid sent by the pump impeller, and a stator disposed between the pump impeller and the turbine runner. The stator converts the direction of flow of the operating fluid circulating from the turbine runner to the pump impeller to the same rotational direction as that of the pump impeller, thereby aiding the rotation of the pump impeller.
In order to achieve a compact torque converter of this type, in a structure in which a thrust bearing is provided on a side face of a one-way clutch that rotatably supports the stator at the inner periphery thereof, as in Japanese Patent Application Publication No. JP-A-2004-132526, the length in the axial direction is reduced by mounting the bearing race of the thrust bearing directly to the outer race of the one-way clutch.
In the torque converter described in Japanese Patent Application Publication No. JP-A-2004-132526, keys protruding inward from the stator are provided to prevent rotation of the outer race and the bearing race, and key grooves mating with the keys are provided in the outer race and the bearing race. It is relatively difficult to machine the keys provided on the stator, and because oil supplied from the oil passage groove of the outer race passes through the key groove, it is necessary to make the key groove of the outer race deep, making it difficult to perform the ordinarily easy task of broaching a key groove in the outer race, and resulting in an increase in the cost of the outer race.